1. Field of the Invention
This invention relates to a self shift type gas discharge panel having a function of shifting discharge spots, and more particularly to a self shift type gas discharge panel in which information written in the form of discharge spots can be sequentially shifted in either of the row and column directions.
2. Description of the Prior Art
There has heretofore been known, as one kind of gas discharge display panel, an AC driven plasma display panel having a matrix type electrode arrangement. This matrix type plasma display panel requires a complicated drive circuit for individually addressing a plurality of electrodes arranged in horizontal and a vertical directions, and has the disadvantage that an increase in the size of the plasma display panel leads to a marked increase in the cost of the drive circuit. To simplify such a drive circuit, there has recently been developed a self shift gas discharge panel having a function of shifting discharge spots.
A typical structure of this self shift gas discharge panel is disclosed in detail, for example, in U.S. Pat. No. 3,944,875 entitled "Gas Discharge Device Having a Function of Shifting Discharge Spots" by Owaki et al. This gas discharge device includes common electrodes disposed on one of a pair of substrates to extend in a horizontal direction (Y) and covered with a dielectric layer and a plurality of shift electrodes disposed on the other substrate to extend in a vertical direction (X) and similarly covered with a dielectric layer. The shift electrodes are sequentially and periodically connected with more than three buses and a shift channel is set up in accordance with the arrangement of discharge points formed between common electrode and shift. At one end of this shift channel, a write electrode is provided for inputting information to be displayed. A discharge spot, which is generated by applying a write pulse to the write electrode, is shifted to adjacent discharge points one after another by sequentially switching shift voltages to buses, utilizing the priming effect due to plasma coupling.
In such an intersecting electrode type self shift gas discharge panel, a plurality of shift electrodes must be sequentially connected with at least three buses on one of the two substrates. Accordingly, in the connection of the buses with the shift electrodes, it is necessary that at least one bus and the shift electrodes connected to the other buses be insulated from each other at the intersections thereof. This insulation is achieved by cross-over techniques but since the formation of such cross-over parts involves troublesome operations, the yield of the panel becomes low and enhancement of reliability of the panel is hindered. Further, in the case of reducing the pitch of the shift electrodes for providing a display with high resolution, the pitch of the cross-over parts is also required to be decreased. This makes the fabirication of the panel more difficult, and seriously hinders the realization of a high-resolution display panel.
Further, U.S. Pat. No. 3,775,764 entitled "Multi-Line Plasma Shift Register Display" by J. P. Gaur discloses a panel structure in which pluralities of parallel shift electrodes are disposed in a back and forth meander pattern on the inside of each of a pair of substrates, respectively, and in which the shift electrodes on each substrate are divided into two groups. This parallel electrode type self shift gas discharge panel eliminates the above-said defect attendant with formation of the cross-over parts, but presents a new problem in the separation of discharge spots in the direction of the shift electrodes, making it difficult to realize a structure capable of providing a high resolution display.
Moreover, U.S. Pat. No. 3,704,389 entitled "Method and Apparatus for Memory and Display" by W. B. McCleland sets forth a panel structure which employs shift electrodes of special patterns so as to shift a discharge spot by making use of the phnomenon that wall charges spread to the wall surfaces of adjoining discharge points. The shift electrodes of the special patterns provide a shift channel like a by-pass. However, this structure is impractical in that no consideration is paid to plasma coupling between adjacent discharge points, and it is very difficult to obtain a practical operation margin.
In view of the above, as panel structures which do not involve the cross-over parts and are excellent in the separation of discharge spots, there have been proposed a meander channel type self shift gas discharge panel, in which row electrodes connected to two-phase buses on one of a pair of substrates and column electrodes connected to two-phase buses on the other substrate are disposed opposite each other with a discharge gas space defined therebetween so that the electrodes on both the substrates extend across each other at right angles and in which a discharge spot is shifted along a shift channel like a by-pass, and a meander electrode type self shift gas discharge panel in which a linear shift channel is formed with sinuous electrodes. These self shift gas discharge panel structures are described in detail in U.S. patent applications Ser. Nos. 810,747 and 813,627 assigned to the same assignee as the present application.
The abovesaid panel structures are now briefly described. FIG. 1 is a diagram explanatory of the electrode arrangement of the meander channel type self shift gas discharge panel. In this discharge panel, column electrodes xai and xbi (i=1, 2, 3, . . . ) respectively connected to column electrode buses Xa and Xb on one of a pair of substrates, and row electrodes yaj and ybj (j=1, 2, 3, . . . ), respectively connected to row electrode buses Ya and Yb on the other substrate, are respectively covered with dielectric layers and disposed opposite each other with a discharge gas space defined therebetween so that the column and row electrodes may extend across each other at right angles. Further, write electrodes wj (j=1, 2, 3, . . . ) are disposed opposite the row electrodes yaj. A discharge spot is shifted along a bypass-like shift channel, for example, in the order of discharge points a-b-c-d- . . . . For the formation of the shift channel, barriers BR are provided between each pair of column electrodes xbi and xa (i+1) between the row electrodes yaj, between each pair of column electrodes xai and xbi between the row electrodes ybj, and between each pair of row electrodes yai and yb (i+1).
FIG. 2 illustrates an example of a series of drive waveforms for shifting a discharge spot in the abovesaid gas discharge panel. The buses Xa, Xb, Ya and Yb are supplied with pulse voltages Vxa, Vxb, Vya and Vyb, respectively. The pulse interval t1 of the pulse Vxa, the pulse width t2 of a shift pulse Vsh and the pulse width t3 of an erase pulse Ve are selected to be, for instance, 15 .mu.S, 5 to 10 .mu.S and 1 to 2 .mu.S, respectively. Reference characters Vaa, Vab, Vbb and Vba show the voltages across the corresponding discharge points as a result of the pulse voltages Vxa, Vxb, Vya and Vyb being applied to the corresponding electrodes.
For example, when a write pulse is applied to the write electrode w1 to produce a discharge spot at the write discharge point a and the shift pulse Vsh is applied to each of the buses Xa and Ya, the voltage indicated by Vaa is fed to the discharge point b, so that the discharge spot shifts to the discharge point b. Next, upon application of the shift pulses Vsh to the buses Xa and Yb, the voltage Vab is fed to the discharge point c to generate a discharge spot at the discharge point c due to plasma coupling, and then the erase pulse Ve is applied to the discharge point b to erase the discharge spot there, thus shifting the discharge spot from the discharge point b to c. Thereafter, the discharge spot is similarly shifted to the discharge points d, e, f, . . . one after another.
FIG. 3 is explanatory of the electrode arrangement of the meander electrode type self shift gas discharge panel. In this discharge panel, two buses XA and XB, electrodes xAi and xBi (i=1, 2, 3 . . . ) alternately connected to the buses XA and XB and write electrodes W1, W2 . . . are formed on one of a pair of substrates, and two buses YA and YB, and electrodes yAj and yBj (J=1, 2, 3, . . . ) alternately connected to the buses YA and YB are formed on the other substrate. The electrodes on both substrates are disposed opposite each other with a discharge gas space defined therebetween. The electrodes have electrode portions xa, xb, ya and yb, respectively, and the opposed parts of adjacent ones of the electrode portions form a unit discharge region, i.e. a discharge point. A dielectric layer is formed at least on each electrode portion.
For shifting the discharge spot, the waveforms shown in FIG. 2 can be used and the discharge spot is shifted in the row direction in which the electrode portions xa and xb are arranged.
The abovesaid meander channel type and meander electrode type self shift gas discharge panels eliminate the need for formation of the cross-over parts, as referred to above, but the structure of these panels allows shifting the discharge spot only in one direction.